1. Field of the Invention
The invention relates to a metal carboxylate derivative of a partially esterified .alpha.-olefin-unsaturated polycarboxylic acid copolymer and to the use of this compound as lubricant or stabilizer in synthetic materials and as emulsifier and/or suspending agent.
2. Description of the Prior Art
A metal carboxylate derivative of the type indicated above is known from U.S. Pat. No. 4,036,810, in which it is described as a stabilizer for chlorine-containing polymers. It is also mentioned as a lubricant for polyvinyl chloride.
Apparently, however, a considerable proportion of the carboxylates obtained by the process of said patent specification consist of compounds whose molecular weight is below 1000 and whose lubricating action is limited.
A metal carboxylate derivative of a partially esterified .alpha.-olefin-unsaturated polycarboxylic copolymer has now been found which is a surprisingly satisfactory internal and external lubricant for synthetic materials. This metal carboxylate derivative is characterized in that at least 80 percent by weight of the unesterified copolymer has a molecular weight in the range of from 1000 to 100,000.
It should be added that DE No. 2,727,329, DE No. 3,003,797 and DE No. 3,136,931 describe partially and wholly esterified .alpha.-olefin-unsaturated polycarboxylic acid copolymers, more particularly .alpha.-olefin-maleic acid copolymers suitable for use as lubricants. The present lubricants distinguish themselves from these copolymers by the presence of metal carboxylate groups, which results in a surprisingly satisfactory lubricating or stabilizing action. Reference is also made to EP No. 54,761, which claims a lubricant consisting of the salt of a copolymer of an .alpha.-.beta.-ethylenically unsaturated acid and ethylene.
The invention also relates to the use of the present compounds as emulsifying and/or suspending agents and they are surprisingly effective as such. For instance, aqueous suspensions of clay can be more satisfactorily stabilized with these compounds than with carboxy methyl cellulose or copolymers from DE No. 3 136 931.